The present invention generally relates to semiconductor manufacturing and more particularly to a method of forming a titanium nitride diffusion barrier layer in middle-of-the-line (MOL) contacts.
In semiconductor technologies, tungsten (W) is typically used as a middle-of-the-line (MOL) contact material mainly because of its relatively low resistance, reduced stress, and electro-migration properties. A MOL contact may be a conductive stud working as an interface between contact areas of an active semiconductor device (or integrated circuit), which may be referred to as front-end-of-the-line (FEOL), and overlying interconnects structures, which may be referred to as back-end-of-the-line (BEOL). MOL contacts may extend to surfaces of contact areas of underlying semiconductor devices. The contact areas of an active semiconductor device may be made of, for example, a silicide material. MOL contacts are usually formed in a layer of dielectric material deposited on top of the active semiconductor device. A plurality of trenches or openings may be formed in the layer of dielectric material to form the MOL contacts.